Factor river sediments

Some studies have also reported PBDE levels in sediments collected near industry facilities. Sellstrom et al. [29] reported total PBDE concentration levels between nd and 364 ng/g dw (nd-360 ng/g dw for BDE-209) in river sediments from a Swedish river with numerous textile industries. Higher PBDE levels up to 1,400 ng/g dw (nd-399 ng/g dw for BDE-209) were found downstream from a foam manufacturing plant using PBDEs in the United Kingdom [31]. BDE-209 burdens up to 4,600 ng/g dw have also been reported on suspended particulates from Dutch surface waters, decreasing with distance from a textile facility [42]. Our PBDE results were considerably higher than those reported for sediments collected near industrial areas, probably because of the small dilution factor of the Vero River at this area, which has an average flow of 2.1 m3/s. 

The major part of the biosphere is aerobic and consequently priority has been given to the study and assessment of biodegradability under aerobic conditions. Nevertheless, there are environmental compartments that can be permanently (e.g. anaerobic digesters) or temporarily anaerobic (e.g. river sediments and soils) and surfactants do reach these. The majority of surfactants entering the environment is exposed to and degraded under aerobic conditions. This is the predominant mechanism of removal even in cases of absence of wastewater treatment practices (direct discharge) and it is estimated that less than 20% of the total surfactant mass will potentially reach anaerobic environmental compartments [1]. Only in a few cases, however, will the presence of surfactants in these compartments be permanent. The presence of surfactants in anaerobic zones is not exclusively due to the lack of anaerobic degradation. Physico-chemical factors such as adsorption or precipitation play an important role as well as the poor bioavailability of surfactant derivatives (chemical speciation) in these situations. 

In another study conducted in river waters and sediments of central Italy, a direct relationship between PAEs concentration levels in water samples fi om rivers and lakes with input of urban or industrial treated wastewaters near the sampling point were also found [82]. They also found an accumulation factor in sediment samples ranging from 10 to 100, showing the trend of PAEs to be absorbed in sediments. DEHP and DBP were found in higher concentration levels than the other seven PAEs investigated. The presence of PAEs in the studied fi eshwaters was closely related to the input of urban and industrial treated wastewaters. DEPH concentrations in freshwater and sediment samples ranged from 0.3 to 31.2 pg/L and from 0.003 to 0.49 pg/g, respectively. 

Abramowicz, D. A., Brennan, M.J., Van Dort, H. M. Gallagher, E. L. (1993). Factors influencing the rate of polychlorinated biphenyl dechlorination in Hudson River sediments. Environmental Science Technology, 27, 1125-31. 

Factor Analysis of the Total Concentrations of Heavy Metals in River Sediments... 

Screening of estuarine and marine sediment samples by automated pyrolysis mass spectrometry combined with factor-discriminant analysis leads to a useful classification related to the geographical position and the sources of the organic matter. The mass spectral data give preliminary information about the organic matter composition. Analysis of the characteristic mass peaks m/z=86 and 100 by PMSMS and PGCMS points to bacterial poly-alkanoates in the mud fraction of the river sediments. 

Atmospheric input of mercury has tripled over the past 150 years. The atmosphere plays an important role in the mobilization of mercury with 25-30% of the total atmospheric mercury burden of anthropogenic origin, although more recent estimates of 67% are significantly higher. As a direct result of human activities, mercury levels in river sediments have increased fourfold since precultural times, and twofold to fivefold in sediment cores from lakes and estuaries. Analysis of sediment cores of North American mid-continental lakes show that mercury deposition rates increased by a factor of 3.7 since 1850, at a rate of about 2% annually. During the past 100 years, more than 500,000 metric tons of mercury entered the atmosphere, hydrosphere, and surface soils, with eventual deposition in subsurface soils and sediments. 

Kodba, Z.C. and Marsel, J., Microwave-assisted extraction and sonication of polychlorobiphe-nils for river sediments and risk assessment by toxic equivalency factors, Chromatographia, 49, 21,1999. 

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